Over-the-Counter Sleep Aids: What Your Options Actually Are

What are the main OTC sleep options and how do they work?

Diphenhydramine (found in Benadryl, ZzzQuil, Unisom SleepTabs, and many others): A first-generation antihistamine whose sedation is a side effect of blocking histamine, not a sleep-specific mechanism. It may help for the first night or two, but tolerance develops quickly — often within days — at which point it no longer aids sleep while still causing side effects: morning grogginess, dry mouth, blurred vision, urinary retention, and constipation.

Doxylamine (Unisom and others): Another first-generation antihistamine with a similar mechanism and side-effect profile to diphenhydramine, somewhat more sedating for some people. The same short-term-only cautions apply.

Melatonin: A hormone the body naturally produces to signal nighttime. Available in a wide range of doses. Melatonin does not cause sedation the way antihistamines do — it shifts the circadian clock. It is most appropriate for jet lag, shift work, delayed sleep phase, and re-anchoring a disrupted schedule 1Ref 1Herxheimer A, Petrie KJ (2002).Melatonin for the Prevention and Treatment of Jet Lag.Melatonin's appropriate use for jet lag and circadian timing problems; low doses are effective; higher doses not more effective. Evidence supports using low doses; higher doses do not appear to work better and may have unintended effects 1Ref 1Herxheimer A, Petrie KJ (2002).Melatonin for the Prevention and Treatment of Jet Lag.Melatonin's appropriate use for jet lag and circadian timing problems; low doses are effective; higher doses not more effective.

Combination products (e.g., Tylenol PM, Advil PM): These combine an antihistamine with a pain reliever. They are appropriate when pain is also contributing to sleep difficulty — but should not be used as routine sleep aids purely for their sedating component. Regular use of acetaminophen or NSAIDs carries its own considerations.

Who should be cautious with OTC sleep aids?

OTC sleep aids are not appropriate for everyone. Use extra caution — or speak with a clinician or pharmacist first — if you:

• Are 65 or older: Diphenhydramine and doxylamine are on the American Geriatrics Society Beers Criteria, a widely used list of medications considered potentially inappropriate for older adults. They increase the risk of falls, confusion, and next-day cognitive impairment in this age group. This is not a minor concern.
• Are pregnant or breastfeeding: Consult your OB or midwife before taking any sleep product, including melatonin, which has limited safety data in pregnancy.
• Have an enlarged prostate or urinary issues: Antihistamines can worsen urinary retention.
• Have glaucoma: Antihistamines can raise intraocular pressure.
• Have a chronic condition (heart disease, liver or kidney disease, COPD, sleep apnea): Multiple conditions interact with these medications.
• Take other sedating medications: Antihistamines compound sedative effects from opioids, benzodiazepines, muscle relaxants, and other antihistamines — a potentially dangerous combination.
• Are using sleep aids more than a few nights a week: This pattern suggests a chronic issue that warrants clinical evaluation, not a stronger or more frequent OTC solution 2Ref 2Kapur VK, Auckley DH, Chowdhuri S, et al. (2017).Clinical Practice Guideline for Diagnostic Testing for Adult Obstructive Sleep Apnea: An American Academy of Sleep Medicine Clinical Practice Guideline.Chronic sleep symptoms warrant clinical evaluation for underlying conditions including sleep apnea before defaulting to sleep aids.

What can OTC sleep aids not do?

The most important thing to understand about OTC sleep aids is what they cannot do: they do not treat the cause of insomnia. They may get you through a difficult night or two — after a stressful event, adjusting to a new time zone, or a transient disruption. They are not designed for, and should not be used to manage, chronic insomnia.

For chronic insomnia (three or more nights a week for three or more months), Cognitive Behavioral Therapy for Insomnia (CBT-I) is the treatment that consistently outperforms medication — including prescription medication — in clinical evidence 3Ref 3Edinger JD, Arnedt JT, Bertisch SM, et al. (2021).Behavioral and Psychological Treatments for Chronic Insomnia Disorder in Adults: An American Academy of Sleep Medicine Clinical Practice Guideline.CBT-I as first-line treatment for chronic insomnia, superior to medication for long-term outcomes4Ref 4Trauer JM, Qian MY, Doyle JS, Rajaratnam SMW, Cunnington D (2015).Cognitive Behavioral Therapy for Chronic Insomnia: A Systematic Review and Meta-analysis.CBT-I outperforms pharmacotherapy for chronic insomnia on long-term outcomes; meta-analytic evidence. CBT-I addresses the mechanisms that sustain insomnia. It is available through trained clinicians, some primary care practices, and increasingly through digital programs. If you have been using OTC sleep aids regularly, a conversation with a clinician about CBT-I is a more productive path.

When should you see a clinician about sleep?

See a clinician if:

• You are using sleep aids more than once or twice a week
• The sleep aids have stopped working, or never worked well
• You have underlying health conditions or take other medications
• You are an older adult considering antihistamine-based products
• Your sleep problems have persisted for more than a few weeks
• You want to understand what is actually causing the difficulty

A clinician can identify whether there is an underlying cause — anxiety, depression, sleep apnea, circadian disruption — and tailor a treatment plan rather than masking the symptoms 2Ref 2Kapur VK, Auckley DH, Chowdhuri S, et al. (2017).Clinical Practice Guideline for Diagnostic Testing for Adult Obstructive Sleep Apnea: An American Academy of Sleep Medicine Clinical Practice Guideline.Chronic sleep symptoms warrant clinical evaluation for underlying conditions including sleep apnea before defaulting to sleep aids.